as far as I know it is not possible to translate that directly into kanji. There is a kanji for foot, take a look here http://en.wiktionary.org/wiki/%E8%B6%B3. But there is no kanji for super, at least I don't know any.

It it possible to use kana (katagana). That is a system the japanese use for foreign words, as computer and western names. So that would use the katagana which are read as "supaafuuto" or something like this.

followed by the one for foot in the above post. The reading would be "Chosoku" and the broad meaning would be similar to the English, although as it is a made up word the level of understanding you would get from native readers will vary somewhat.

However, as touched on above, I have only ever seen Bill Wallace's "superfoot" nickname written phonetically in Japanese martial arts magazines etc so the katakana version would perhaps be more familiar. Both "super" and "foot" are words recognised by most Japanese even if they don't speak English.